Three-dimensional (3-D) viewing units and electronic image display units according to the prior art have been described in Japanese Laid Open Patent Applications H5-107482 and H9-511343. As described in Japanese Laid Open Patent Application H5-107482, surgical microscopes that image light fluxes, convert the images into electrical signals, and then display the images are advantageous in that a weaker light can be used to illuminate ophthalmic operations. The weaker illuminating light not only presents less of a problem if directed directly into a patient's retina, but it also reduces surface evaporation due to the light at the illuminated surface being converted into heat. Thus, less saline solution is needed during an operation to prevent the operation site from drying out. However, prior art surgical microscopes using electronic displays retain the following obstacles to increased usage.
1) They provide less freedom to the main operator in his viewing position and head orientation (hereinafter viewing position and head orientation will be termed, for convenience, viewing posture). Further, the assistant operator is provided with very limited viewing postures, namely, either directly opposite the operator facing the operator or at the operator's side facing a direction that makes a right angle to the forward direction of the operator.
2) When the operator and assistant share a common optical system, the prior art devices require too much adjustment. For example, when the operator and assistant take side-by-side positions, they share an optical viewing system between them. Three optical zoom systems are usually provided in order to offer the user a selection of magnifications with which to view the operation. However, it is very difficult to adjust the optical axis, magnification, and co-focus of the three optical zoom systems for multiple viewers. Thus, it is desired for surgical microscopes using electronic displays to provide more freedom in terms of viewing posture of the operator and assistant without requiring complex adjustments of the optical system.
3) In order that multiple users, such as both the operator and assistant, can have an independent observation capability, prior art surgical microscopes that use electronic displays provide each viewer with an individual imaging system and individual optical viewing system. However, this results in an increase in size of the surgical microscope, more difficulty in adjustment, and greater cost as compared to the present invention.
In prior art surgical microscopes that provide wide-angle, 3-D images, the viewers must wear polarized glasses as they view a large display monitor that displays wide-angle images. If polarized glasses are not used, the left eye receives not only the images displayed on the monitor intended for the left eye, but also the images having parallax that are intended for the right eye. Similarly, the right eye also sees double images. Thus, rather than experiencing wide-angle, 3-D images, the viewer experiences only blurred 2-D images if polarized glasses are not worn. Further, both wide-angle images and proper eye relief may not be realized at the same time in prior alt devices.
Prior art devices relating to problems (1), (2), and (3) above are discussed in more detail below.
Japanese Laid Open Patent Application H 9-511343 describes a method to reduce the number of optical zoom systems. However, no consideration is given to the limited viewing postures available to the operator and assistant or of giving these viewers more freedom of viewing posture.
Japanese Laid Open Patent Application H5-107482 describes an example of a 3-D viewing system according to the prior art, wherein two viewers view an operation site from positions that are opposed to each other. This example is described with reference to FIGS. 20-22. FIG. 20 is a schematic front elevation view of such a device. FIG. 21 is a side view of the device shown in FIG. 20, and FIG. 22 is a partial, top view which illustrates the opposed directions in which the two pairs of monitors are directed. A microscope body 106′ (FIG. 20) comprising an optical system and imaging section is provided with a viewing section supporting member 138 (FIG. 21). The viewing section supporting member 138 is provided with rotation axes 134, 134′ for rotationally supporting the back of viewing sections 130, 130′, as well as a first left monitor 131 for the left eye (FIG. 20) having an eye shade 131a and a first right monitor 132 for the right eye having an eye shade 132a. These side-by-side monitors are connected to the viewing section 130′ by a rotation supporting member 133 (FIG. 20). Similarly, a second left monitor 137 for the left eye (FIG. 22) and a second right monitor 136 for the right eye are provided to the viewing section 130′. As shown in FIG. 22, the monitors 131, 132 display to the left in the figure and the monitors 136, 137 display to the right in the figure.
Therefore, by orienting the detecting devices that are fixed within the microscope body so that the left and right parallax images that are detected are displayed with a correct vertical orientation for the user, each operator is provided with a 3-D viewing experience using tile viewing sections 130, 130′. In this case, the operators do not need to wear polarized glasses. Rather, a monitor is provided for each eye, each eye views only its monitor, and no obstacles to viewing, such as the wearing of polarized glasses, are present. However, a wide-angle 3-D image is not obtained and the viewing positions are limited to the opposed positions illustrated. Viewing at the side of the operator is not available. Because a user has little freedom in choice of viewing postures, the viewing experience may be tiresome.
As mentioned previously, the field of view is limited in systems that use two display units (for instance the left and right monitors 131, 132) in order to provide images to the left and right eyes, respectively. In order to display wide-angle images, both the left and right display panels would need to be enlarged. However this would cause the two display panels to physically interfere with each other. In addition, in this prior art device, each imaging section is provided with an optical zoom system. Enlarging these optical zoom systems would likely lead to adjustment problems and oversized systems.
Japanese Laid Open Patent Application H5-107482 also describes another prior art device of a 3-D viewing system, wherein the operator and assistant view at right angles to each other. This embodiment is described with reference to FIGS. 23-25. FIG. 23 is a schematic side view of a prior art 3-D viewing system that shows how two side-by-side viewers view 3-D images while facing 90 degrees to each other. FIG. 24 is a block diagram of the microscope body and electric wiring of this device. FIG. 25 is a top view showing the locations of optical paths P, Q, R (each passing light of different perspective relative to the operation site) which are detected by solid-state image detecting devices positioned within the microscope body 199. As shown in FIG. 23, the microscope body (not separately labeled in this figure) is fixed to a supporting arm 156 which is provided with liquid crystal monitors 193, 194. Being supported so as to be spatially movable, the microscope body 199 (FIG. 24) is provided with an illumination system (not shown), an objective lens 110, three magnifying systems 161a, 161b, 161c, and relay lenses 162a, 162b, 162c. Further, a solid-state image detecting device 200, 201, or 202 is positioned in the optical paths P, Q, or R (FIG. 25), respectively, with the solid-state image detecting device 202 having an orientation that is rotated counter-clockwise 90° relative to the orientation of the solid-state image detecting device 201.
In this prior art device, in 3-D image circuit 185A, an internal switching circuit (not shown) alternates in time sequence picture signals Fl and picture signals A as input signals to create time-multiplexed image signals which are output to a liquid crystal monitor 193. A liquid crystal driving circuit (not shown) drives electrodes attached to the back surface of the liquid crystal monitor 193 so as to rotate the polarization of the displayed images in synchronism with the switching of the switching circuit Thus, at the liquid crystal monitor 193, the time-multiplexed picture signals A detected from the optical path Q and the picture signals F1 detected from the optical path P are displayed with different polarizations. By wearing polarized glasses (not shown), cross-talk between these images is avoided, thereby enabling the left eye of the viewer to see only those images captured from a left perspective optical path, and the right eye of the viewer to see only those images captured from a right perspective optical path. Thus, a viewer experiences a 3-D viewing sensation of the operation site 111. In a similar manner, the 3-D image circuit 185B and the liquid crystal monitor 194, display picture signals F2 on the optical path P and the picture signals C on the optical path R, in a time-division manner, with different polarizations. Polarized glasses worn by the other viewer prevent the images intended for that viewer's right eye (i.e., the images from a right perspective optical path) from entering the viewer's left eye, and vice-versa. Thus, each viewer perceives 3-D images of the operation site 111. According to this prior art device, three optical viewing paths are used. One path is observed by one operator, one path is observed by the other operator, and one path is shared so as to be observed by both operators. The images on the path they share are processed so as to present a correct vertical orientation to each operator. Each operator is provided with two images (one for each eye) having parallax, with the display images having a proper vertical orientation for each viewer's position relative to the operation site so as to create the perception of viewing a 3-D image with proper orientation for that viewer's position. In addition, more free space is available to the operators because the circuit parts are all stored within tables and the microscope body may be small, since the optical objective 110 is shared. However, in this prior art device, the operator and assistant can only view from positions such that the directions of view are at a right angle to each other; thus, the viewing postures are again limited. In this prior art device, no consideration is given to providing a pair of liquid crystal monitors that may be adjusted about the axis of the microscope body so that the monitors are easier to view or so that the operator's viewing posture may be varied. Furthermore, an optical zoom system must be provided for each image detecting device, which makes adjustment troublesome and the size of the microscope larger. Furthermore, this device requires the operators to wear polarized glasses, which is inconvenient.
Japanese Laid Open Patent Application H9-511343 also describes prior art electronic image input and output techniques that employ time-multiplexing and demultiplexing. First, the electronic image input technique in this publication will be described. A zoom lens is shared in the image input section, and the left and right images are input in a time-division manner. This will be described with reference to FIGS. 26 and 27. FIG. 26 is a schematic diagram showing an improvement in inputting and outputting electronic images. FIG. 27 is a top view of an optical path switching element of the prior art device. As shown in FIG. 26, right and left optical paths 101a, 101b and a rotation switch element 103a are provided. As shown in FIG. 27, the rotation switch element 103a is structured on a thin glass plate (disk) 105. One of the major characteristics of the optical paths 101a, 101b is that the distances along both paths from the object (at the operation site) to optical zoom system 113 are the same. Similarly, the distances along both paths from the object to image detecting device 109 are equal. This results from the symmetry of the two mirrors 138a, 138b about the center axis of main objective lens 108. Images are captured by the image detecting device 109 in a time-division manner using the rotation switch element 103a. Next, the electronic image output technique that is disclosed in this publication for demultiplexing these time-multiplexed left and right images will be discussed.
FIG. 28 is a horizontal sectional view illustrating the configuration of a device disclosed in the above-mentioned publication that demultiplexes the two time-multiplexed images. As shown in this figure, the images are displayed on a single display which alternately feeds light from the display into to two ocular lens paths 101c and 101d in synchronism with the displayed images. In this device, equal length optical paths are realized using a prism. An optical path switching element 103a allows alternate images from the display to be transferred to the ocular paths 101c, 101d in a time-division manner. Thus, the left eye of a viewer will receive only images having a left perspective and the right eye of a viewer will receive only images having a right perspective if the motor that drives the optical path switching element 103a is properly synchronized with the alternately displayed left and right images on the single monitor. In this manner, a color 3-D viewing experience may be provided that does not require the viewer to wear polarized glasses. However, this prior art device can not realize both a wide-angle field of view and have a large eye relief. Further, this publication does not disclose, when using multiplexing/demultiplexing of the images, how two operators (e.g., an operator and the assistant) can view an object while sharing a common optical objective, or how they may change their viewing postures and have the images that are presented automatically be adjusted in orientation for the new viewing posture. Therefore, a surgical microscope which is desirable for operators as described above is not realized.